In the histology of the avian primary lymphoid organ known as the Bursa of Fabricius, which specialized epithelium is responsible for transporting antigens from the lumen to the underlying lymphoid follicles?

In the mammalian lymph node, which specific histological region is primarily composed of T-lymphocytes and characterized by the presence of High Endothelial Venules (HEVs)?

Regarding the histology of the spleen, which specific structure consists of an arteriole surrounded by a sheath of T-lymphocytes, representing the thymus-dependent zone of this organ?

Which histological feature is uniquely characteristic of the thymic medulla and consists of concentric layers of flattened epithelial reticular cells?

In veterinary histology, which animal species is known for having an 'inverted' lymph node structure where the distribution of red and white pulp-like areas results in the cortex being centrally located and the medulla being peripheral?

In the histology of the spleen, what is the name of the region that separates the white pulp from the red pulp and acts as a key site for the filtration of antigens and aged blood cells?

In the histology of the mammalian lymph node, which specific structure acts as the primary conduit for lymph as it first enters the organ through the afferent lymphatic vessels?

In the histology of the tonsils, what term is used to describe the deep, invaginated passages lined by epithelium that increase the surface area for contact between the environment and the lymphoid tissue?

In the histology of the thymus, which cell type forms the structural framework of the parenchyma and contributes to the 'blood-thymus barrier' through its tight junctions?

In the histology of the mammalian spleen, which structure consists of an arteriole surrounded by specialized macrophages and a thick basement membrane, serving as the final segment of the arterial system before blood enters the splenic sinuses or cords?